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' R. EIOKEMEYER.

SPEAKING TELEPHONE. No. 249,233. Patented Nov. 8,1881.

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' I SPEAKINGTELEPHONE. No. 249,233. Patented Nov. 8,1881.

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UNITED STATES PATENT OFFICE.

' U OLFEIOKEMEYER, or YONKERS, NEW YORK.

SPEAKING-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 249,233, dated November 8, 1881.

' Application filed July 13, 1881. (No model.)

To all whom t't may concern Be it known that I, RUDoLF ErcKnMEYnR, of Yonkers, in the State of New York, have invented 'a new and useful Improvement in Speaking-Telephones, of which the following is a specification.

The invention. relates to that class of speaking-telephones in which the transmission of articulate speech is due to the variations in the resistance of the electric circuit; and it consists in an improved device for producing said variations in resistance, the essential parts thereof being aplatinum strip forming one electrode, and arranged to partake of thevibrations of an ordinary diaphragm, and a triangular film of carbon, slightly curved, as hereinafter described, and forming the second electrode. The platinum strip and carbon film are placed lengthwise with each other, and are always in contact; but as the platinum strip takes up the vibrations of the diaphragm the surface of the film of carbon remaining in contact with the platinum strip, or with which contact is made by the platinum strip, varies both lengthwise and breadthwise. The film of car: bon is exceedingly thin, and is always at rest.

In the drawings, Figure 1 is a plan of a transmitting-instrument embodying my invention, the diaphragm and a part of the mouth-piece having been removed. Fig. 2 is avertical section ofsaidinstrument. Fig. 3 gives two views of a rubber dampener. Fig. 4 is a diagram illustrating, so far as is necessary, the mode of operation. Fig. 5 is a partial section, on an enlarged and exaggerated scale, to show the relative locations of the electrodes and parts to,which they are attached. Fig. v6 is a detail, to which especial reference is hereinafter made.

A is the bed-piece.

B is the base of a frame, adjustable upon the bed-piece by means of screws 8 5 working in slots t t, as shown. C is the upper part of said frame, furnishing a seat for the diaphragm D, which is held therein by a mouth-piece, E, in the ordinary manner, there being a dampening-cushion, 6, around the edge of the diaphragm. The base and top part of the frame are connected, as shown,

made adjustable in length by means of thumbscrews Gr.

by three posts, F,

H is a plate of ivory, hard rubber, or glass, supported by twometallic posts, J J, in which, respectively, are the binding-screws a a, to which are attached the line-wires l l. A hole is cut through the middle of the plate H, opposite' the center of the diaphragm, and in this hole is set a piece of platinum, p, which is connected with the metallic post J ,by a wire, w. 'There is also on the top of the plate H a film of carbon. 0, triangular in shape, forming one of the electrodes, as stated above, the wider part of the film resting upon the piece of platinum p, which fills the hole in the plate H.

K is the strip of platinum referred to aboye asthe other electrode. It is held in place, in part upon and in part above the plate H, by two bands, being a bridge or block, cl, to separate the platib b, screwedto the plate H, there num strip from the plate at one end, as shown.

One end of the platinum strip is in contact with the metallic post J, as shown.

P is a rod firmly secured to the platinum stri p K,and also to the diaphragm D, whereby the vibrations of the diaphragm are communicated to the electrode or platinum strip.

. L is a bar, screwed at one end to the inner side of the top portion of the frame, and two rubber dampeners, r 1', one on either side of the diaphragm, are held between this bar and the mouth-piece. These rubbers serve also as washers for the nut and flange used in securing the part 1? to the diaphragm, as shown in Fig. 6.

R is anadjust-ing-screw, its upper end pressing against the plate H under that portion covered by the carbon film c, at about the mid dle of the latter longitudinally, and giving to both plate and film a slight curve longitudi nally in the normal adjustment of the apparatus. The relation of the electrodes to each other when at rest, or the initial resistance of the line, is regulated by this screw B, and it vary with the vibrations of the diaphragm. This is shown by the diagram at Fig. 4, where the three perpendicular cross lines in the lower part of the figure illustrate the variations in the width of the film in contact with the plati num strip, while the tangential lines to theplateH in the upper part of the figureillustrate 2. 111 a speaking-telephone, substantially as the variations in the length of carbon film in described, the means for adjusting the second contact with the platinum strip, the film itself electrode and giving to it a curved surface connot being shownin the upper part of the figure, sisting of the carbon film itself, the plate H, 20

on account of its exceeding thinness. clamped at each end,andtheadjusting-screwR. Aniuduction-coil may be used with this sole 3. The diaphragm D, post P, and platinum phone in theordinary manner. strip K, in combination with theplate H, bridge I claim d, platinum plugp, carbon film c, and line-con- 1. The platinum strip K, partaking ot' the motions, substantially as described. vibrations of the diaphragm and forming one of the electrodes, in combination with the dia- RUDOLF EIGKEMEYER. phragm and a film of carbon, with an insulating bed therefor, the said film being of vary- Witnesses:

ing width and curved longitudinally upon its HENRY OSTERHELD,

said bed, and forming the second electrode, GEORGE NARR.

substantially as described. 

